shaun3000
Posts: 439
Joined: Thu Mar 14, 2002 4:10 pm

Cessna 172 Flaps

Sat Oct 04, 2003 2:32 am

I don't know why I just thought of this, but here it goes. I took my private checkride, over a year ago, in a 172. The check pilot asked me what kind of flaps the 172 had. I told him Fowler, since they slid back on a track when set to one notch, and then lowered when more flaps were commanded.

He said I was wrong and they were slotted. We had a good discussion about it, and I said they shoudl be Fowlers since they slid back more than down on the first setting and increased wing area. But the POH said slotted, so that's what he wanted. (It didn't affect me, though, I sill passed. haha)

SO, what kind of flaps does a Cessna 172 have? Slotted or Fowler?
 
aaron atp
Posts: 517
Joined: Sun Mar 19, 2000 1:17 pm

RE: Cessna 172 Flaps

Sat Oct 04, 2003 4:10 am

If you are going to call them fowler flaps, you would need to call them "single slotted fowler flaps"

I think that given the 175 ft2 surface area, the extra <7.5 square feet from the flap travel isn't that noticeable. Therefore, calling them slotted is probably more correct. I think the official word from Cessna is indeed 'slotted.'

7.5 ft2 equates to a 4.2% increase in surface area for an aircraft at 2300 lbs is not completely neglibable (<100 lbs by rough mental math [L= Cl q S], but probably <50 lbs considering the TE design of the wing). However, I think if I had time to do the math I could show you that it isn't nearly as important (effective) as it is for jet aircraft that are equipped with double/triple slotted fowlers. Compared to the lift increase due to change in camber, the lift due to extra sfc area is irrelevant on the C172.

Maybe someone who has worked with C172 graphs more recently could come up with actual numbers.

So I haven't actually told you anything in this post, but at least look at it as a different way of evaluating the problem.

aaron



 
NWA
Posts: 1162
Joined: Fri Jun 22, 2001 2:31 am

RE: Cessna 172 Flaps

Sat Oct 04, 2003 5:19 am

The last test I had in my flight class, thats the only one I missed. That is correct, they are slotted. The jeppesen books say they are fowler though.
23 victor, turn right heading 210, maintain 3000 till established, cleared ILS runwy 24.
 
SkyGuy11
Posts: 532
Joined: Fri Oct 26, 2001 7:09 am

RE: Cessna 172 Flaps

Sat Oct 04, 2003 5:46 am

Grab ASA's Pilot's guide... they're slotted with a fowler action over the first 10*. Though the POH itself just says slotted...
.
 
Guest

RE: Cessna 172 Flaps

Sat Oct 04, 2003 6:44 am

Interesting. I probably would have said "fowler" too. Well, it just goes to show you should read your POH. Actually, I DID get that question on my CFI checkride. I had to teach a lesson on Airplane Flight Controls (or whatever the exact name of that Technical Subject Area was.) And I did say that Cessna flaps were fowlers. And I didn't get any challenge on it. In fact, I would have just gone on thinking that Cessna flaps were fowlers if I hadn't read this thread.

Now, the flaps on the Warrior/Archer/Arrow--THOSE are slotted flaps.

-Normal
 
Ralgha
Posts: 1589
Joined: Tue Nov 09, 1999 6:20 pm

RE: Cessna 172 Flaps

Sat Oct 04, 2003 10:44 am

Slotted flaps: similar to plain flaps with the addition of allowing some air from beneath the wing to pass through a slot to the top of the wing.

Fowler flaps: When extended, the Fowler flap moves rearward as well as down.

Cessna flaps fit both definitions. Nowhere does it say that you can't combine types of flaps.
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